I used two different search engines to find Magic Strips and both offered the non-stretch (Wilton type) bake-even strips called by various names....
Only stretchable stips I found were Rose's Heavenly Cake Strips which are silicone and only fit 8-9" square/round pans:
Is the material stretchy in the Magic Strips? If so, I don't think it could be as thick/dense as the bake-even strips material (so would hold less water).
The bake even strips can be easily adjusted by using either a large paper clip or small/medium binder clip, instead of the t-headed pins included.
You can also purchase bake even strips that are secured by Velcro so they adjust easily:
(Or add your own heavy duty Velcro.)